An alcohol fuel such as ethyl alcohol, a benzene fuel of the petroleum benzene type or a liquid gas fuel such as butane gas or propane gas is generally used as the fuel of a cigarette lighter, fire-lighting device, torch, lamp or other such burner.
The performance, ease of use, and structural design of such burners differs depending on the kind of fuel used, and each has its own characteristics. In the case of a liquid gas fuel, for instance, the gas pressure is high in the use temperature range of the burner and the vessel storing the fuel has to have a pressure-resistant structure. Moreover, the flame length changes with variation in the gas pressure and since it is a characteristic of the gas pressure to vary logarithmically and greatly with temperature, large change in flame length with temperature becomes a particular problem. In order to reduce this flame-length variation, the fuel supply mechanism of the burner requires a special design countermeasure for affecting temperature compensation, which complicates the structure and is disadvantageous from the aspect of cost.
In contrast, since a liquid fuel such as an alcohol fuel is a liquid at ordinary temperatures and is also relatively low in vapor pressure, it does not require a pressure-resistant vessel in the fuel storage section and, as such, simplifies the structure of the burner and is advantageous from the aspect of cost. Further, in the liquid fuel burner, the means used to supply the liquid fuel from the fuel storage section to the flame-producing section is generally a wick that utilizes the surface tension of the liquid fuel to draw it up through continuous fine holes or fine voids among bundled fibers by capillarity and burns it at the tip portion thereof.
Specifically, the wick used for drawing up the fuel is a string-like one obtained by twisting fibers, one obtained by bundling fibers, one using both of these with the glass fibers enclosed in cotton yarn and the result interwoven with fine metal wires to prevent disintegration, or the like, whose the lower end portion functions to draw up fuel to be burned at the upper end tip portion.
The flame-producing section of the wick has to be sealed by an openable/closeable closure cap in order to prevent evaporation of the liquid fuel during nonuse. In addition, a striker wheel or other igniter must be installed near the wick for scattering sparks to light the wick.
Since the closure cap is ordinarily installed to open and close about a pivot at one end portion thereof, its cap portion for sealing the flame-producing section of the wick passes along an arcuate path and, therefore, when it is attempted to make such a lighter or other burner compact, the need to prevent interference of this path with the wick tip portion, the wick holder, the striker wheel etc. hinders the size reduction.
Particularly, as regards sealing of the portion of the wick holder of the wick, the sealing end portion of the closure cap must interpose between the wick holder portion and the igniter, e.g., striker wheel, in order to enable covering of the peripheral portion of the wick holder portion, and if the igniter is spaced away from the wick in order to avoid interference of the sealing end portion with the igniter, a problem of igniting performance degradation may arise because of, for example, the elongated spark travel distance. Good igniting performance is therefore preferably secured by disposing the igniter near the wick.
On the other hand, when the igniter is installed closer to the wick, the flow of air around the flame changes to impede inflow of secondary air to the flame in proportion as the igniter is disposed nearer the flame and the flame tends to swell toward the igniter side so that its edge portion comes near or in contact therewith. The temperature of the igniter (e.g., striker wheel) is therefore liable to rise. When the striker wheel is heated, the heat may, for example, be conducted to its plastic support portion to melt the support portion. The striker wheel may then be detached by the pressing force of the flint urged against the striker wheel, making it useless.
In addition, when a wick made by merely bundling glass fibers or other fiber material is used and the glass fiber bundle at the tip portion of the wick are undone and spread out by contact of the end portion of the closure cap with the wick tip or contact of the object to be lit (e.g., cigarette) with the wick tip, the flame thickens, as shown in FIG. 8 to be explained later, to possibly approach the igniter (e.g., striker wheel) and, at the same time, the sealing portion of the closure cap is liable to catch a portion of the frayed wick tip and be degraded in evaporation preventing performance.
In consideration of the foregoing circumstances, this invention aims to provide a wick for a liquid fuel burner that by changing the shape of the flame-producing section enables the igniter to be located near the wick while avoiding interference with the closure cap.
The invention further aims to provide a liquid fuel burner which by changing the shape of the wick holder enables the igniter to be disposed at a position near the wick to ensure good igniting performance, while avoiding interference with the closure cap, and also avoids elevated temperature states by preventing swelling of the flame toward the igniter side.